Dengue fever epidemic is spreading: Part 1

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dengueThe dengue fever epidemic in India is getting worse and spreading globally. We reached out to our Zintro experts for their opinions on the dangers of dengue fever and the potential impact on populations as it spreads.

 Dr. Awosika-Olumo, MD., MS., MPH., PhD, an expert in infectious disease prevention and control, says that dengue fever is a viral disease of public health importance in terms of human morbidity and mortality that is transmitted by mosquitoes. “Annually, an estimated 100 million people are affected by the disease worldwide. Dengue fever is an acute febrile illness characterized by frontal headache, retro-ocular pain, muscle pain, joint pain, and rash. The illness is caused by any of the four different serotypes of the dengue virus,” he says. “The common clinical presentations associated with an infected patient are a sudden onset fever lasting for 2-7 days; intense headache; myalgia; arthralgia; retro-orbital pain; anorexia; nausea; vomiting; and rash. A probable case of dengue is a clinically compatible case with supportive serological findings: a reciprocal IgG antibody titer of greater or equal to 1280 or a positive IgM anti-body test on a single acute (late) or convalescent phase serum to one or more Dengue Virus antigens.”

 

Awosika-Olumo explains that there are four different serotypes Dengue virus (DENV), designated DENV-1, DENV-2, DENV-3, and DENV-4. “DENV belongs to the genus Flavivirus and family Flaviviridae. Flaviviruses are enveloped, single stranded, positive-sense RNA viruses. DENV is transmitted to humans by Stegomyia aegypti (formerly Aedes aegypti) mosquitoes. The incubation period from the time of infectious bite to symptoms is 3 to 14 days and averagely, 4-7 days. The mosquito becomes infective 8-12 days after the viremic blood meal and remains so for life. Person-to-person transmission has been documented in rare instances of blood-borne or tissue mediated transmission via transfusions and bone marrow transplantation,” he says.

 

Before the 1980s, Awosika-Olumo says, epidemic dengue was rare in the Americas because Stegomyia aegypti had been eradicated from most Central and South American countries. By the 1990s, Stegomyia aegypti had almost completely reinvaded the regions in which it was found before its eradication. Within the past 30 years, the increase in the http://www.zintro.com/expert/adebowale-awosika-ol, as well as uncontrolled population growth and urbanization, has led to larger and more frequent DENV epidemics and more cases of DHF/DSS.

 

“According to World Health Organization, about 2.5 billion people, or 40% of the world’s population, live in areas where there is a risk of dengue transmission. Dengue is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean. WHO estimates that 50 to 100 million infections occur yearly, including 500,000 DHF cases and 22,000 deaths, mostly among children,” says Awosika-Olumo, “The full life cycle of dengue fever virus involves the role of mosquito as a transmitter (or vector) and humans as the main victim and source of infection. It currently occurs in tropical areas.”

 

Awosika-Olumo outlines the measures that can be taken against dengue fever:

Preventive Measures

  • Educate the public and promote behaviors to remove, destroy or manage mosquito vector larval habitats.
  • Surveillance:
    • Disease surveillance: To determine the number of infected human cases,
    • Vector Surveillance: To determine the abundance of vector mosquitoes, identify the most productive larval habitats, and promote and implement plans for their elimination.
  • Personal protection against day-biting mosquitoes through repellents, screening and protective clothing.

Control of patient, contacts and the immediate environment

  • Case reporting to health authority,
  • Isolation: Isolate patients to prevent day-biting mosquitoes to patients by screening the sickroom or using mosquito nets,
  • Investigation of contacts and source of infection,
  • Specific treatment: Supportive including oral rehydration; Acetylsalicylic acid (aspirin) is contraindicated because of its bleeding potential.

Vector control

  • Transmission control activities should target Ae. aegypti or any of the other vectors depending on the evidence of transmission in its immature (egg, larva, and pupa) and adult stages in the household and immediate vicinity. This includes other settings where human–vector contact occurs, such as schools, hospitals and workplaces.
  • Use mosquito repellents for people exposed to vector mosquitoes.
  • Observing whether behaviors aimed to reduce dengue transmission are adopted and sustained by the community.

 

Mark Bonifacio, an expert in medical device manufacturing, notes that while dengue fever is a serious illness, it is typically only fatal in a small number of cases; most cases can be treated with Tylenol and hydration, including I.V. in more severe cases. “There does not appear to be a vaccine available in the next few years. There were some potential candidates that were identified, but they have not been effective in stopping this virus,” says Bonifacio. “India has increased it’s spraying in an attempt to lower the mosquito population; however, most experts believe this will have a minor effect on the proliferation. With that said, and until there is an effective vaccine in place, it will be very hard to control this epidemic. Clothing, mosquito repellent, and netting can help reduce exposure to mosquitoes. Traveling during periods of minimal mosquito activity can also be helpful. Areas most affected by dengue are inIndia, parts of the Caribbean, Asia, and South and Central America.”

A related story can be found here.

By Maureen Aylward

 

 

 

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